The present invention relates to a system for projecting a virtual image within an observer's field of view.
There are various known systems for projecting virtual images which are used in display devices wearable by a user and are known in the field as Head Mounted Displays, or HMDs. Some of these, which are known as see-through displays, enable a virtual image to be seen superimposed on the image of the real world. Others, which are known as non-see-through displays (for example, virtual-reality helmets or viewers for palmtops such as the commercial models produced by Sony, Canon and Olympus) enable solely a virtual image to be seen. Yet others, which are known as see-around displays (for example, MicroOptical's products) have a display screen inserted within the user's field of view. In general, all of the known systems are constituted basically by three subsystems: a micro-display which generates the real image, an optical system which focuses it at the desired distance (typically at infinity), and an optical system for projection within the user's field of view. However, the incorporation of these subsystems in a single wearable device, for example, of the spectacles type, involves problems of complexity, size and weight.